OBJECTIVE: The objectives of this population-based study were to examine the use of emergency medical services (EMS) in greater Worcester, Massachusetts, residents (2000 census = 478,000) hospitalized with acute myocardial infarction (AMI) at all metropolitan Worcester medical centers in four biennial periods between 1997 and 2003. A secondary study aim was to describe the demographic and clinical characteristics of patients with AMI transported to metropolitan Worcester hospitals by EMS, compared with those transported by other means, and their hospital outcomes.

METHODS: We reviewed the medical records of 3805 patients hospitalized for confirmed AMI at 11 greater Worcester medical centers during 1997, 1999, 2001, and 2003. Information about the use of EMS, patient characteristics, and hospital outcomes was obtained through the review of hospital charts.

RESULTS: A total of 2693 greater Worcester residents with AMI (70.8%) were transported to area hospitals by ambulance. Patients transported by ambulance were older, were more likely to be women, had a greater prevalence of comorbidities, and had a different symptom profile than patients transported by other means. Patients arriving at greater Worcester hospitals by ambulance were more likely to develop serious clinical complications, including heart failure and cardiogenic shock, and die during hospitalization compared with patients not transported by EMS.

CONCLUSIONS: Our results suggest that the majority of greater Worcester residents seeking care for AMI are transported by EMS. Patients transported by ambulance differ from patients transported by other means and are more likely to experience adverse hospital outcomes. The reasons why patients use EMS in the setting of AMI need to be further explored and patients' care-seeking behavior enhanced.